Calipers and dividers.



UNITED STATES aTnNT tribe..

LAROY S. STARRETT, OF ATHOL, MASSACHUSETTS, ASSICNOR TO THE L. S.STARRETT COMPANY, OF SAME PLACE.

CLlPERS AND DIVIDERS.

SPECIFICATION forming part of Letters Patent No. 672,424, dated April16, 1901.

Application filed April 5, 1900. ierial No. 11,597. (No model.)

To a/ZZ whom it may con/037%:

Be it known that I, LAROY S. STARRETT, of Athol, in the county ofWorcester and State of Massachusetts, have invented certain new anduseful Improvements in Calipers and Dividers, of which the following isa specification.

This invention relates to the class of calipers and dividers in which,in addition to the general movement of the two legs on their pivot,provision is made for their accurate adjustment overcomparatively-limited distances by means cfa short supplementary arm andan adjusting-screw. An instance of this general construction is found inthe Letters Patent No. 539,759, granted to me May 2l, 1895.

The object of my present improvement is to provide for these tools anadjusting device adapted for dividers and for both inside and outsidecalipers, such device in no Way limitingthe general movement of the legsand having also a Wider range of adjustability than those hithertoknown. The adjusting-screw is mounted for rotation without longitudinalmovement in a suitable bracket connected to one of the legs, and thethreaded body of said screw engages the thread of a swiveled nut mountedon the free end of the supplementary arm, whereby the rotation of suchscrew moves the leg to which such bracket is secured toward or from theother leg, Which is made fast frictionally on the pivot, while thefirst-named leg has more freedom of movement thereon. The bracket ismounted on the outer face of the leg which carries it and has a i'latbase extending across such face, and the free end of the arm is offsetoutwardly enough -to pass over or lie outside of such bracket-base. Thelegs and arm are connected by an enlarged axially-threaded pivot toreceive the short arm on which the vadjusting-screw acts.

In the drawings, Figure l is a plan view of my instrument. Fig. 2 is alike View of the same tool used as an inside caliper. Fig. 3 is alongitudinal section on line 3 3 of Fig. l. Fig. I is a transversesection on line 4 4 of Fig. l. Fig. 5 represents some of the partsdetached.

A and B are the two legs, and C the supplementary arm, all connected attop by a suitable pivot. The preferred form shown has a stoutsubstantially cylindrical rivet lD,.in ternally threaded, formed with abroad flange at one end and squared at the other, where the short arm Cis mounted. Washers E are interposed between the parts and all are heldvwith proper friction by the broad-headed screw F, the stem of whichengages the thread in rivet D. The washer, which adjoins leg B, is shownin Fig. 5 as formed with .a projection e to enter a groove in pivot D;but this is not essential. The arm C has a square hole at one end to iiton the squared tip of rivet D, and its other end, as shown in Figs. 3and 5, is offset outwardly from leg A to a distance about equal to itsthickness and then continues in its former direction parallel to saidleg. On this offset part C', I mount a swiveled nut G, provided with areduced stem passing through and turning in a perforation in the part Cand'headed to prevent withdrawal. A bracket H is secured transversely tothe outer face of leg A, its fiat body extending across said leg beneaththe offset part C' of the arm C, said bracket at its outer end beingturned up and perforated to receive the cylindrical stem of theadjusting-screw J, the threaded body of which engages the threads of theswiveled nut G. A radial collar on the screw-stem bears against the faceof the upturned end of the bracket. The milled head J of the screw J isaffixed to its smooth stem on the opposite side of the bracket, thuspreventing endwise movement of the screw. I

My improved construction is very advantageous. The bracket H, being bentataright angle, lies at one end between leg A and the nut G, swiveled onthe offset part of arm C, While the upturned end of said bracket formsIOO an admirable bearing for the adjusting-screw, which engages saidnut. The swiveled nut G turns in its bearing as the rotation of thescrew J swings the supplementary arm C through a short arc, (or rathermoves the leg A on its pivot with relation to said arm.) This swivelaction prevents any tendency to bind or cramp the adjusting-screw at theextreme ends of the swinging movement, since the parts aline themselvesin use of the tool. If the adjusting-screw is greatly prolonged, thebracket I-I will turn slightly on the rivet 7L, which unites it to theleg A.

I claim as my invention- In calipers and dividers, the legs A B ad-

